A conventional polygonal nut or bolt, such as a hexagonal nut N as shown in FIG. 1, is rotatably driven by a socket S having polygonal or hexagonal sides H when tightened or loosened. The apex or corner line L of each apex of polygonal nut N will be linearly bitten or dogged by the polygonal side H of the socket S. After repeated uses, the corners of the nut or bolt will be worn or damaged to cause loosening or slipping of the nut or bolt in the socket to thereby influence a tightening or loosening operation of the nut or bolt.
Meanwhile, the nut or bolt, when worn, will be oxidized by the environment to be rusty or corroded. Such a conventional nut or bolt will be damaged or presented with poor appearance.
The present inventor has found the drawbacks of the conventional polygonal nut and bolt, and invented the present anti-wearing nut and bolt.